Amperometric sensor

• US 7,608,180 B2
• Filed: 12/21/2005
• Issued: 10/27/2009
• Est. Priority Date: 06/29/1999
• Status: Expired due to Fees

• Current Assignee: Drew Scientific Holdings, Inc.
• Original Assignee: Drew Scientific Holdings, Inc.
• Inventors: Slater, Jonathan Mark, Lau, Kim King Tong
• Primary Examiner(s): NOGUEROLA, ALEXANDER STEPHAN
• Application Number:
  US11/312,486
• Publication Number:
  US 20060096859A1
• Time in Patent Office: 1,406 Days
• Field of Search: 205/777.5, 205/778, 205/792
• US Class Current: 205/777.5
• CPC Class Codes: C01B 15/01 Hydrogen peroxide
• CPC Class Codes: C01C 3/12 Simple or complex iron cyanides
• CPC Class Codes: C07C 211/63 having quaternised nitrogen atoms bound to acyclic carbon atoms
• CPC Class Codes: C12Q 1/004 mediator-assisted
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 27/3271 Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001

Abstract

An amperometric sensor suitable for determining the concentration of hydrogen peroxide in a sample, the sensor comprising a ferricyanide compound which, in reduced form, functions as a mediator specific to hydrogen peroxide.

Claims

1. A method for determining the concentration of H₂O₂ in a sample containing H₂O₂, which method comprises:

providing a sensor comprising 2 or 3 electrodes, one of the electrodes being coated with a ferricyanide compound which in reduced form functions as a mediator selective for hydrogen peroxide, wherein the ferricyanide compound has a low solubility in an aqueous phase,

applying a potential of about −

400 mV to the sensor, such that the oxidised form of the mediator is reduced to the reduced form,

contacting the sensor with the sample, such that the H₂O₂ oxidises the reduced form of the mediator to the oxidised form,

maintaining the applied potential of about −

400 mV such that the oxidised form of the mediator generating a current,

measuring the generated current.

2. A method according to claim 1, wherein the ferricyanide compound is of general formula:

X₃Fe(CN)₆

in which the groups X are the same or different and at least one X is a non-metallic ion.

3. A method according to claim 2, in which each X is a quaternary ammonium ion of formula (R¹) (R²) (R³) (R⁴) N⁺ in which R¹ to R⁴ are the same or different alkyl groups containing from 1 to 20 carbon atoms, provided that at least one of R¹ to R⁴ contains at least 4 carbon atoms.

4. A method according to claim 3, wherein the ferricyanide compound is tetrahexylammonium ferricyanide, tetrakisdecylammonium ferricyanide, tetradecyltrimethylammonium ferricyanide, hexadecyltrimethylammonium ferricyanide or trimethylhexylammonium ferricyanide.

5. A method according to claim 2, wherein each X is a nitrogen-containing heterocyclic cation.

6. A method according to claim 5, wherein each X is a pyridinium ion.

7. A method according to claim 2, wherein each X is a phosphonium ion of formula (R⁵) (R⁶) (R⁷) (R⁸) P⁺ in which R⁵ to R⁸ are the same or different alkyl groups containing from 1 to 20 carbon atoms, provided that at least one group R⁵ to R⁸ contains at least 4 carbon atoms.

8. A method according to claim 1, in which the ferricyanide compound is bound to a polymer.

9. A method according to claim 8, wherein the polymer is a polyacrylamide.

10. A method according to claim 8, wherein the ferricyanide compound is bound to the polymer via one of groups R¹ to R⁴ of a quaternary ammonium ion of formula

(R¹)(R²)(R³)(R⁴)N⁺

or via one of groups R⁵ to R⁸ of a quaternary phosphonium ion of formula

(R⁵)(R⁶)(R⁷)(R⁸)P⁺

or via a nitrogen-containing heterocyclic cation.

11. A method according to claim 8, wherein the ferricyanide compound is polypyridinium ammonium ferricyanide or poly(acrylamide-co-diethyldimethyl ammonium)ferricyanide.

12. A method according to claim 1, wherein the solubility of the ferricyanide compound in water is from 2,000 to 20,000 mg/l.

13. A method for determining the concentration of an analyte in a sample, which analyte is capable of producing H₂O₂ when contacted with an analyte, the method comprising:

contacting the sample with an enzyme such that the analyte in the sample reacts with the enzyme to produce H₂O₂

providing a sensor comprising 2 or 3 electrodes, one of the electrodes being coated with a ferricyanide compound which in reduced form functions as a mediator selective for hydrogen peroxide, wherein the ferricyanide compound has a low solubility in an aqueous phase,

applying a potential of about −

400 mV to the sensor, such that the oxidised form of the mediator is reduced to the reduced form,

contacting the sensor with the sample, such that the H₂O₂ oxidises the reduced form of the mediator to the oxidised form,

maintaining the applied potential of about −

400 mV such that the oxidised form of the mediator generating a current,

measuring the generated current.

14. A method according to claim 13, wherein the enzyme is provided on an electrode.

15. A method according to claim 13, wherein the analyte is glucose and the enzyme is glucose oxidase.

16. A method according to claim 13, wherein the ferricyanide compound is of general formula:

X₃Fe(CN)₆

in which the groups X are the same or different and at least one X is a non-metallic ion.

17. A method according to claim 16, in which each X is a quaternary ammonium ion of formula (R¹) (R²) (R³) (R⁴) N⁺ in which R¹ to R⁴ are the same or different alkyl groups containing from 1 to 20 carbon atoms, provided that at least one of R¹ to R⁴ contains at least 4 carbon atoms.

18. A method according to claim 17, wherein the ferricyanide compound is tetrahexylammonium ferricyanide, tetrakisdecylammonium ferricyanide, tetradecyltrimethylammonium ferricyanide, hexadecyltrimethylammonium ferricyanide or trimethylhexylammonium ferricyanide.

19. A method according to claim 16, wherein each X is a nitrogen-containing heterocyclic cation.

20. A method according to claim 19, wherein each X is a pyridinium ion.

21. A method according to claim 16, wherein each X is a phosphonium ion of formula (R⁵) (R⁶) (R⁷) (R⁸) P⁺ in which R⁵ to R⁸ are the same or different alkyl groups containing from 1 to 20 carbon atoms, provided that at least one group R⁵ to R⁸ contains at least 4 carbon atoms.

22. A method according to claim 13, in which the ferricyanide compound is bound to a polymer.

23. A method according to claim 22, wherein the polymer is a polyacrylamide.

24. A method according to claim 22, wherein the ferricyanide compound is bound to the polymer via one of groups R¹ to R⁴ of a quaternary ammonium ion of formula

(R¹)(R²)(R³)(R⁴)N⁺

or via one of groups R⁵ to R⁸ of a quaternary phosphonium ion of formula

(R⁵)(R⁶)(R⁷)(R⁸)P⁺

or via a nitrogen-containing heterocyclic cation.

25. A method according to claim 22, wherein the ferricyanide compound is polypyridinium ammonium ferricyanide or poly(acrylamide-co-diethyldimethyl ammonium)ferricyanide.

26. A method according to claim 13, wherein the solubility of the ferricyanide compound in water is from 2,000 to 20,000 mg/l.